The human eye, in simple terms, functions to provide vision by transmitting and refracting light through a clear outer portion called the cornea and focusing the image by way of the lens onto a light-sensitive tissue lining the inner surface called the retina. The quality of the focused image depends on many factors including the size, shape, and length of the eye, and the shape and transparency of the cornea and lens.
Unfortunately, trauma, age, or disease may cause a variety of problems with the eye (e.g., cataracts or retinal detachment). However, many surgical procedures have been developed that allow repair to various part of the eye (e.g., lens and retina). During these surgeries, fluids may need to be introduced into the eye (e.g., to maintain intraocular pressure or to manipulate eye components). These fluids are typically introduced through cannulas, which are basically long, straight tubes that are inserted into the eye.